Aluminium in fermenting beer

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oxonbrew

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Hi,

I'm trying to build a DIY brewjacket (peltier/TEC immersion chiller for fermenting).

I'm wondering if I can use a standard aluminium rod attached to the peltier to chill the fermenting beer? Or is it unsafe to have aluminium in contact with wort/beer??

Any help would be great.

Cheers!
 
The Brewjacket uses an anodized aluminum rod. You may want to look into going that route.

Maybe someone more knowledgeable can chime in about using raw aluminum.
 
The acidity of fermenting beer will eventually eat away at bare aluminum. Although the thermal conductivity of stainless is quite a bit lower than aluminum or copper, the corrosion resistance is much better for that environment.
 
Thanks for the responses - both very helpful.

I have a stainless rod, but am concerned about the low thermal conductivity. I've looked for anodized aluminium rods and cant find anything suitable. I've thought about using the peltier in an air cooled fermentation chamber, but running at max I can only achieve about 15 degree drop in air temperature from ambient, so potentially would work, but its very inefficient. I don't have any extra room for a fridge/freezer, does anyone have any other suggestions for a material to use as the rod, or other ways to maintain lager fermentation temps?

Cheers.
 
The conductivity of the rod shouldn't matter as long as you have enough surface area. The cooling capacity is going to be based on the capacity of the peltier cooler (which aren't very efficient).

The specific heat of water, as a wort approximation, (4.1855kJ/kgK) is was different then air (1.00 kJ/kg.K) so you are going to need more cooling capacity to make a temperature CHANGE. Temperature holding is just overcoming heat loss, although air will change faster. Do you have insulation installed? That would be the biggest help.

You could make a glycol chiller out of a window A/C and either get a tight coil to fit into the fermenter or wrap the outside with hose.
 
It's been about a month since the last post. Has anyone found a suitable anodized rod? The 36"x1-1/2" rod at McMaster is $88, and if cut in half would make two 18" rods. I don't think a 12" rod will be long enough for my 30L Speidel tanks. The cut side could be tapped to allow it to be screwed onto a plate attached to the peltier.

The description says it's coated, but does that mean an additional coating over the anodized layer, or are they including the layer as a "coating"? Would this rod be safe and appropriate for brewing?

In my mind I have various versions of this mostly figured out, including a "dumb" version that would just plug into my usual temp controller, and a standalone version similar to the commercial one (using an Arduino and an H-bridge) that both heats and chills, with possible future upgrades including data logging, and wifi and/or bluetooth monitoring/control (once I improve my coding abilities). But I haven't been able to find a suitable anodized rod, so I haven't really delved too deep into the project.

So, any reason not to use the McMaster rod linked above?
 
Just received a reply from McMaster:
"Our aluminum rods are not rated as food-safe or for FDA compliance. We cannot make a recommendation for your application."

Doesn't mean they're not food safe, just that they're not rated as such. Worth the risk?
 
Get copper. It'll be a little pricey but worth it. Probably have a local machine shop order a piece for you. They could face, drill, and tap it for you too.

All the Best,
D. White
 
Get copper. It'll be a little pricey but worth it. Probably have a local machine shop order a piece for you. They could face, drill, and tap it for you too.

All the Best,
D. White

I vaguely recall reading somewhere (copper auto-siphon thread, I think) that the green oxidation on copper could pose a health hazard. Is there any way to anodize/passivate copper to prevent oxidation?
 
Aluminum is fine. People have been using aluminum for cooking pots forever, and of course for brewing kettles - and reactions are much faster at high temperatures.

Aluminum will form an oxidation layer which will actually protect the aluminum surface.

Same with copper. Many industrial sized mash tuns are made of copper. As well as manifolds, immersion chillers, counter-flow chillers etc.

Copper is a better thermal conductor, though.

pH is not a concern. wort is 5.2 and the beer will get into 4's, but so is spaghetti sauce (pH of 4.5 or so) and diet sodas have pH around 2.5 and served in aluminum cans.
 
I'm a big advocate for copper over stainless, but if the wall thickness is thin enough the thermal conductivity difference isn't going to hurt you much.. Maybe you can even increase the surface area to compensate by larger diameter tubing or a couple of loop backs. You can find SS tubing pretty cheaply right now on e-bay, and you can silver solder to it just like copper if need be. I'd still consider it. If I had to do it over again, I would have made my homemade "linear" CFC 60 ft of stainless and PEX instead of out of copper and PEX at 50 ft like I did. I bet it would work exactly the same...
 
While I know and have used both aluminum and copper during the brew day, the OP's original question, an my own, are about trying to clone a BrewJacket Immersion, which uses a sold rod of anodized aluminum submerged into fermenting beer for the duration of fermentation (plus lagering if so doing), which is attached to a peltier device that basically sucks the heat out of the beer. Despite the name it's not an immersion wort chiller.

So I'm looking for something that can (safely) stand up to the conditions of fermenting/lagering beer for 3-8 weeks. Are bare copper or aluminum safe for this kind of application?

Also, aluminum cans are usually coated with a non-reactive coating prior to filling because bare aluminum will react with the contents and give the acidic foods/beers off flavors. Anodized aluminum, however, has been rendered non-reactive by the anodizing process.
 
Put the aluminum rod in the stainless tube, or use stainless tube and circulate alcohol or even distilled water through it. I suppose I did not realize that a Brew Jacket worked that way. Must be a big Peltier Junction to be effective at all on five gallons. We used to have an anodizing tank at work but the chemicals are so nasty that they send it all out now. However many machine shops will still have the ability. I think when done the stuff is pretty non reactive but can be scratched off fairly easily. Liquid in a tube should be looked into. Even convection can work well.
 
Put the aluminum rod in the stainless tube, or use stainless tube and circulate alcohol or even distilled water through it. I suppose I did not realize that a Brew Jacket worked that way. Must be a big Peltier Junction to be effective at all on five gallons.
Interesting idea, we'll call it the "All-Clad Approach". Bare aluminum is easy enough to find. Now the difficult part will be finding a stainless "sleeve".

From the BrewJacket website the housing is 5.5" square, so I'd imagine the heatsink and fan are 4-5". However, the rod they use is 1.5", and I imagine it'd be a waste of energy having a peltier much larger than that. Even they admit it's not for fast chilling beer, but more for maintaining temps, which is supposedly easy enough for the peltier to handle.


We used to have an anodizing tank at work but the chemicals are so nasty that they send it all out now. However many machine shops will still have the ability. I think when done the stuff is pretty non reactive but can be scratched off fairly easily. Liquid in a tube should be looked into. Even convection can work well.
I might be able to find someone local to anodize for me. I'd thought about anodizing it myself, but you're right - the chemicals involved are rather gnarly!
 
The Rod is 1.5" in diameter.. interesting. You have the potential then for running multiple tubes instead and using Aluminum rod from a home store and cladding it with stainless tubing, or like I said circulating some liquid through multiple runs of tubing. You could potentially design and build something that is even more effective that way.

Of course, when I looked into that doing something like that in the past I just converted the old dorm fridge I had.. ;) Even that thing struggles to cold crash, though. It's fine for lagering and ales though. This is why I said it must be a large Peltier. Anyway, best of luck with the project. It will be interesting to see what you come up with.
 
Of course, when I looked into that doing something like that in the past I just converted the old dorm fridge I had.. ;) Even that thing struggles to cold crash, though. It's fine for lagering and ales though.

That's why I'm looking into this project. Of course, my "ugly junk" fermentation chamber is just a dorm fridge foil-taped to some pink foam board insulation and leftover shelving. It's not pretty, but it does maintain (seasonally appropriate) temperatures. Can't do lagers in the summer, and cold crashing is impossible without 6 inches of ice forming around the "freezer". So I thought a BrewJacket knockoff might be useful.

Slightly :off:, but I found a comment on their initial Kickstarter page that they had initially been using 12v 8a peltiers that they had been overheating, but "The new set of PSUs that we have in now are able to handle that amperage far more efficiently and only heat to a maximum of 110ºF, so warm to the touch, but not hot. We have been stressing each PSU at 125% and 150% of maximum load for an extended period of time and we haven't seen temperature increases in the PSU beyond safe levels or failures any of our new set of units."

Thoughts on these more efficient PSUs? Same peltier with a better fan/heatsink?
 
Gotcha. I've only played with surplus Peltiers in the past, and I don't know what is good and bad, probably only that bigger is better. I suspect from that comment they did switch vendors of the actual Peltiers..

I've been kinda looking out for a cheap, working small used chest freezer to replace the dorm fridge. Even on old inefficient one will work in this application because most of the time it will be off (even 50F lager temps are, meh, to a freezer). I can get my fridge down to the low 40's but it takes a week from 70F... so... ....I hear ya.

Fred
 
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